Mobile communications devices with movable displays, also known as audio displays have visual display screens which are able to function as a loudspeaker as well as a visual display screen. Such displays are movable by flexing for example and this generates sound waves.
Existing audio displays are difficult to use in products such as mobile phone handsets and tablet computers for a variety of reasons. For example, the movement of the display is typically very small so that low frequency reproduction is very modest making it difficult for sound reproduction requirements to be met. As a result users may be unable to perceive the audio signal correctly leading to communication problems.
Another issue with audio displays in general concerns privacy. As the whole audio display emits sound, then in the case of a mobile phone handset where the whole display emits sound, many people in the vicinity of the handset are able to hear the emitted sound in addition to the user of the mobile phone handset. This is found to be the case even where the user's ear is against the display surface.
The embodiments described below are not limited to implementations which solve any or all of the disadvantages of known audio devices.